1. Field of the Invention
The present invention relates to the field of injection molding. In particular, the present invention relates to a heater clamp which secures a heater element around a cylindrical injector barrel used to inject thermoplastic materials into molds.
2. Description of the Prior Art
Injection molding is a production process for converting thermoplastic materials into molded articles of relatively intricate shapes, at fast production rates, and with good dimensional accuracy. The basic injection molding process for thermoplastics involves the injection, under high pressure, of a predetermined quantity of heated and plasticized material into a relatively cool mold, where the material solidifies and from which the resultant product is subsequently removed.
A helical heater element is held in close thermal contact with a round cylindrical barrel by a clamp designed to provide uniform clamping pressure so the heater is in uniform thermal contact with the injector barrel. The heater element, the clamp, and the injector barrel are disposed in a blind hole where space is limited. The heater clamp must be tightened while the clamp is in place in the blind hole.
A problem with prior art clamps using adjusting screws at right angles to the barrel axis has been the difficulty of using a tool (hex key, Allen wrench, screwdriver, etc.) to turn the adjustment screw in the injection molding machine. When the screw extends across the blind hole, it can be difficult to see the screw and a maintenance person has difficulty in adjusting the screw. Visibility from the front of the blind hole is blocked by a female mold which can be slid only a limited distance away from the injector barrel without disassembling the production setup. The swing or travel of the adjusting tool on a screw conventionally mounted is restricted by the blind hole and the clamp itself so that the tool may have to be reinserted several times to complete an adjustment. It is desired to have a clamp which can be tightened using a tool that can be easily placed on the tightening screw for the clamp.